5.1 Tidal Range Energy Conversion Concepts
3 min read•august 7, 2024
harnesses the power of tides using barrages and lagoons. These structures create head differences between water levels, driving to generate electricity. Understanding these systems is crucial for grasping tidal energy's potential.
Tidal barrages and lagoons operate in different modes: ebb, flood, and . Each mode has its pros and cons, affecting efficiency and environmental impact. Mastering these concepts is key to optimizing tidal energy conversion.
Tidal Barrage and Lagoon Systems
Tidal barrage structures
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Cardiff Bay Barrage, Sluice Gates © Colin Smith :: Geograph Britain and Ireland View original
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Tidal power - Wikipedia View original
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Cardiff Bay Barrage, Sluice Gates © Colin Smith :: Geograph Britain and Ireland View original
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Top images from around the web for Tidal barrage structures
Cardiff Bay Barrage, Sluice Gates © Colin Smith :: Geograph Britain and Ireland View original
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ESSD - Measurements of hydrodynamics, sediment, morphology and benthos on Ameland ebb-tidal ... View original
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Tidal power - Wikipedia View original
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Cardiff Bay Barrage, Sluice Gates © Colin Smith :: Geograph Britain and Ireland View original
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ESSD - Measurements of hydrodynamics, sediment, morphology and benthos on Ameland ebb-tidal ... View original
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- is a dam-like structure built across a tidal estuary or bay to capture from the tides
- Consists of turbines, , embankments, and ship locks
- Turbines are located at the base of the barrage to generate electricity as water flows through
- Sluice gates are opened to allow water to flow into the basin during high tide and out during low tide, creating a
- Ship locks allow vessels to pass through the barrage safely (Panama Canal)
Tidal lagoon systems
- Tidal lagoons are similar to tidal barrages but are constructed as self-contained structures along the coastline
- Lagoons can be natural or artificial enclosures that fill with water during high tide and release it during low tide
- Artificial lagoons are created by building a wall or embankment to enclose a portion of the coastline (Swansea Bay project, UK)
- Tidal lagoons have less environmental impact compared to barrages since they do not block the entire estuary or bay
Generating head difference
- Head difference refers to the difference in water level between the basin and the sea
- Sluice gates are opened during high tide to allow water to flow into the basin, raising the water level inside
- During low tide, the sluice gates are closed, creating a head difference between the higher water level in the basin and the lower sea level
- The head difference drives the flow of water through the turbines, generating electricity
- The greater the head difference, the more potential energy is available for conversion into electrical energy
Tidal Barrage Generation Modes
Ebb generation
- mode operates during the outgoing (ebbing) tide
- Sluice gates are opened during high tide to fill the basin and closed at the beginning of the ebb tide
- Water is released from the basin through the turbines as the tide falls, generating electricity
- Ebb generation is the most efficient mode since it utilizes the maximum head difference between the basin and the sea (La Rance Tidal Power Plant, France)
Flood generation
- mode operates during the incoming (flooding) tide
- Sluice gates are opened during low tide to empty the basin and closed at the beginning of the flood tide
- Water flows into the basin through the turbines as the tide rises, generating electricity
- Flood generation is less efficient than ebb generation due to the smaller head difference available
Two-way generation
- Two-way generation mode combines both ebb and flood generation
- Turbines generate electricity during both the incoming and outgoing tides
- Sluice gates are used to control the flow of water and optimize the head difference
- Two-way generation increases the overall energy output but requires reversible turbines that can operate in both directions (Annapolis Tidal Power Plant, Canada)
Turbine operation modes
- Turbines in tidal barrages can operate in different modes depending on the generation scheme
- In ebb generation, turbines operate as water flows out of the basin, rotating in a single direction
- In flood generation, turbines operate as water flows into the basin, rotating in the opposite direction
- Two-way generation requires reversible turbines that can operate efficiently in both directions
- Bulb turbines, Straflo turbines, and Kaplan turbines are commonly used in tidal barrages due to their ability to handle large flow rates and low head differences
Key Terms to Review (23)
David F. Henty: David F. Henty is a prominent figure known for his contributions to the field of tidal and wave energy, particularly in the development of tidal range energy conversion technologies. His work focuses on innovative methods for harnessing tidal energy efficiently and sustainably, influencing both academic research and practical applications in renewable energy. Henty's expertise has been instrumental in advancing our understanding of tidal dynamics and energy extraction methods.
Ebb generation: Ebb generation refers to the process of harnessing energy from tidal currents as water flows out of an estuary or bay during the ebb phase of a tidal cycle. This phase occurs after high tide, when the water level begins to decrease and the gravitational pull from the moon and sun causes water to flow back toward the ocean. Ebb generation is an essential aspect of tidal range energy conversion concepts, as it utilizes the kinetic energy created by moving water to generate electricity.
Feed-in Tariff: A feed-in tariff is a policy mechanism designed to encourage the development of renewable energy sources by guaranteeing fixed payments for energy produced from renewable resources over a specified period. This financial incentive helps to reduce investment risks for developers and promotes the integration of clean energy technologies into the power grid, fostering innovation and sustainability in the energy sector.
Flood generation: Flood generation refers to the process of creating a tidal surge or increase in water level due to the gravitational forces exerted by celestial bodies, particularly the moon and the sun. This phenomenon leads to varying tidal ranges, which can significantly affect coastal areas and is critical for harnessing energy through tidal range energy conversion methods.
Fluid Dynamics: Fluid dynamics is the branch of physics that studies the behavior of fluids (liquids and gases) in motion. This field is crucial for understanding how energy can be harnessed from ocean movements, such as waves and tides, as it provides insights into the forces and flow patterns that can impact energy conversion systems, efficiencies, and designs. Fluid dynamics principles help engineers predict how water interacts with structures and devices that capture ocean energy, enabling them to optimize performance and reliability.
Graham E. H. Hargreaves: Graham E. H. Hargreaves is a notable figure in the field of tidal energy research and engineering, recognized for his contributions to understanding tidal range energy conversion concepts. His work has helped advance the development of technologies that harness the power of tidal currents and water levels, thus facilitating efficient energy generation from renewable sources. Hargreaves' studies often focus on optimizing energy extraction methods and addressing engineering challenges associated with tidal energy systems.
Habitat alteration: Habitat alteration refers to the changes made to natural environments by human activities or natural events that can significantly impact the species living in those habitats. This concept is crucial in understanding how energy projects, particularly tidal and wave energy systems, can modify coastal ecosystems, affecting both the physical and biological aspects of these environments.
Head Difference: Head difference refers to the vertical distance between two water levels, typically between high tide and low tide in tidal energy systems. This difference is crucial for determining the potential energy available for conversion into usable power, as greater head differences can generate more energy. Understanding head difference is essential for designing efficient tidal range energy conversion systems that can harness this energy effectively.
Hydrodynamics: Hydrodynamics is the study of fluids in motion, particularly focusing on the forces and interactions that occur when water flows. This field is crucial for understanding how ocean energy systems harness wave and tidal movements, which are influenced by factors like flow velocity, pressure distribution, and fluid behavior around structures.
Levelized Cost of Energy: Levelized Cost of Energy (LCOE) is a measure used to compare the overall costs of generating energy across different sources, representing the per-unit cost (typically in dollars per megawatt-hour) of building and operating a generating plant over its lifetime. It allows for a straightforward comparison between energy sources, including renewables like tidal and wave energy, by accounting for all relevant expenses such as capital, operational, and maintenance costs, as well as the expected energy production.
Marine ecosystem effects: Marine ecosystem effects refer to the impacts that human activities, such as energy extraction, have on marine environments and the organisms that inhabit them. These effects can include changes in habitat structure, alterations in species composition, and shifts in nutrient cycling, which can disrupt the balance of marine ecosystems. Understanding these effects is crucial when considering the implementation of tidal range energy conversion technologies, as they can have far-reaching implications for biodiversity and ecological health.
Mean Sea Level: Mean sea level (MSL) is the average height of the ocean's surface, measured over a specific period of time, usually taken as the average of high and low tides. This measurement is critical for understanding tidal ranges and basin characteristics, as it serves as a baseline for determining variations in sea level due to tides, weather, and other factors. MSL provides essential reference points for energy conversion systems that utilize tidal ranges, enabling engineers to optimize designs based on predictable fluctuations in water height.
Potential Energy: Potential energy is the stored energy in an object due to its position or state. In the context of ocean energy, potential energy plays a crucial role in how water levels and gravitational forces can be harnessed for energy generation, particularly in tidal and wave energy systems. The variations in sea level and tidal range are essential factors that determine the amount of potential energy available for conversion into usable power.
Renewable Energy Standards: Renewable energy standards are regulations that require a certain percentage of energy production to come from renewable sources, such as wind, solar, and tidal energy. These standards are designed to promote the use of clean energy, reduce greenhouse gas emissions, and encourage investment in renewable technologies. By setting clear goals for renewable energy adoption, these standards influence the development and implementation of various energy conversion systems, including tidal range energy and wave energy converters.
Return on Investment: Return on Investment (ROI) is a financial metric used to evaluate the profitability or efficiency of an investment relative to its cost. In the context of renewable energy, particularly ocean energy, ROI plays a crucial role in assessing the viability of projects, comparing the potential financial returns from ocean energy systems against their installation and operational costs. This evaluation helps stakeholders make informed decisions about investments in technologies such as tidal and wave energy.
Sluice Gates: Sluice gates are structures that control the flow of water through a channel, typically used in tidal energy systems to manage water levels and regulate water flow. They are crucial for the operation of tidal barrage systems, allowing water to be let in or out at specific times to optimize energy production from tidal ranges. These gates play a key role in maintaining the balance between inflow and outflow, ensuring that energy conversion is efficient and effective.
Tidal Amplitude: Tidal amplitude refers to the vertical distance between the high tide and low tide water levels. It is a critical factor in understanding how tides behave and can vary significantly depending on various influences such as the geographical features of a coastline and the positions of the moon and sun. Recognizing tidal amplitude is essential for assessing tidal range and its implications for energy conversion technologies, as larger amplitudes can result in more significant energy generation potential.
Tidal Barrage: A tidal barrage is a dam-like structure built across the entrance of an estuary or tidal river that harnesses the potential energy generated by the difference in water levels between high and low tides. This system captures and utilizes tidal energy by allowing water to flow through turbines during both incoming and outgoing tides, making it a significant method for converting tidal range energy into electricity. The construction of tidal barrages is heavily influenced by local tidal phenomena and the driving forces behind tides.
Tidal Lagoon: A tidal lagoon is an artificial body of water that is created by enclosing a section of the coastline with a dam or barrier, designed to capture and harness the energy produced by tidal movements. This setup allows for the generation of renewable energy through turbines placed in the structure, making it a viable solution for converting tidal range into usable electricity. Tidal lagoons are particularly beneficial because they can provide predictable energy output and have the potential for additional uses such as recreational activities and habitat creation.
Tidal Range Energy: Tidal range energy is the energy derived from the difference in height between high and low tides, which can be harnessed to generate electricity. This phenomenon occurs due to the gravitational pull of the moon and sun on Earth's waters, creating a predictable pattern of rising and falling water levels. Tidal range energy conversion relies on this natural rhythm to transform kinetic and potential energy into usable power, making it a promising renewable energy source.
Turbine operation modes: Turbine operation modes refer to the different ways in which turbines can function to convert kinetic energy from water flow into mechanical energy, specifically in the context of tidal range energy conversion. These modes are crucial for optimizing energy extraction based on varying tidal conditions, ensuring efficiency and effectiveness in harnessing tidal power. Understanding these modes helps in designing systems that can adapt to changing environmental factors and maximize energy output.
Turbines: Turbines are mechanical devices that convert kinetic energy from fluids, such as water or air, into mechanical energy. In the context of tidal and wave energy systems, turbines play a crucial role in harnessing energy from water movement, enabling the conversion of tidal range energy into usable power. They are key components in various tidal energy systems, impacting efficiency and performance in energy generation.
Two-Way Generation: Two-way generation refers to a tidal energy system that captures energy during both the incoming and outgoing tides, allowing for energy generation in both directions of tidal flow. This method enhances energy capture efficiency by utilizing the full tidal cycle, which can lead to a more consistent and reliable energy output. Such systems can significantly improve the economic viability of tidal energy projects by maximizing the available energy resources throughout the tidal phases.